Airborne radar systems are widely used to assist pilots in avoiding obstacles and unfavorable weather ahead of the aircraft. For convenience of description, the term “pilot” is intended to include any person who is operating and/or viewing the radar images and not merely the person who is controlling the aircraft and the terms “storm” or “storms” are intended to include any type of weather disturbance detectable by the radar but especially thunder storms. As used herein, the term “thunderstorms,” whether singular or plural, is intended to refer to cumulonimbus storms. These are convective storms that have significant moisture content. Such storms usually involve rapidly rising and sometimes violent columns of moisture ladened air that can extend to high altitudes. Typical thunderstorms are often, for example and not intended to be limiting, 5 to 20 nautical miles (NM) wide and about 45,000 to 50,000 feet tall. They often produce internal lightening bolts and heavy turbulence, which can adversely affect aircraft passing through them. Thunder may occur as a natural consequence of the lightening. Other types of moisture containing storms, such as stratocumulous storms, usually occur at lower altitudes (e.g., less than about 15,000 feet) and extend over large distances, e.g., 50–200 nautical miles (NM). They generally lack the strong convective currents of thunderstorms and typically have less impact on aircraft. Accordingly, airborne weather radar systems are most often applied to the detection and avoidance of thunderstorms.
Several problems that can arise in connection with airborne weather radar systems are: (i) minimizing pilot involvement in detecting the presence of thunderstorms in the flight path, (ii) determining thunderstorm location and shape relative to the aircraft, (iii) presenting the thunderstorm image on the radar display in such manner that it is easy for the pilot to grasp its location, size and relative impact on aircraft operations, and (iv) reducing the terrain related background images (collectively referred to as “ground clutter”) that can sometimes accompany thunderstorm images making them difficult to identify. Various approaches have been developed to deal with these problems. Automatic antenna scanning can be used to reduce the need for the pilot to manually steer the radar beam in the vertical dimension (referred to as manual antenna tilt). Color is used in the radar display to indicate radar return intensity, thereby giving visual feedback on the echo intensity in various directions and ranges. For example, green is often used for echoes from weak precipitation (e.g., from ˜1 to ˜4 mm/hr precipitation rate), yellow for echoes from intermediate precipitation (e.g., from ˜4 to ˜11.5 mm/hr precipitation rate), red for echoes from heavy precipitation (e.g., from ˜11.5 to ˜49.5 mm/hr precipitation rate) and magenta for echoes from extreme precipitation (e.g., more than ˜49.5 mm/hr precipitation rate). Further, various techniques have been developed for removing at least some of the ground clutter from the radar returns presented to the pilot along with the weather data. However, a need for further improvement in weather radar systems and methods continues to exist.
Accordingly, it is desirable to provide improved weather radar systems and methods so that radar storm images, especially thunderstorm images, are more readily visualized and understood by the pilot, thereby facilitating operational comfort and improved safety. In addition, it is desirable that this be accomplished with minimal change to conventional radar hardware. Furthermore, other desirable features and characteristics of the present invention will become apparent from the subsequent detailed description and the appended claims, taken in conjunction with the accompanying drawings and the foregoing technical field and background.